142 lines
4.3 KiB
Python
142 lines
4.3 KiB
Python
import re
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import six
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from cassandra.cluster import UserTypeDoesNotExist
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from cassandra.util import OrderedDict
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from cassandra.cqlengine import CQLEngineException
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from cassandra.cqlengine import columns
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from cassandra.cqlengine import connection
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from cassandra.cqlengine import models
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class UserTypeException(CQLEngineException):
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pass
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class UserTypeDefinitionException(UserTypeException):
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pass
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class BaseUserType(object):
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"""
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The base type class; don't inherit from this, inherit from UserType, defined below
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"""
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__type_name__ = None
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_fields = None
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_db_map = None
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def __init__(self, **values):
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self._values = {}
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for name, field in self._fields.items():
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value = values.get(name, None)
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if value is not None or isinstance(field, columns.BaseContainerColumn):
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value = field.to_python(value)
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value_mngr = field.value_manager(self, field, value)
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if name in values:
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value_mngr.explicit = True
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self._values[name] = value_mngr
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def __eq__(self, other):
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if self.__class__ != other.__class__:
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return False
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keys = set(self._fields.keys())
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other_keys = set(other._fields.keys())
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if keys != other_keys:
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return False
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for key in other_keys:
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if getattr(self, key, None) != getattr(other, key, None):
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return False
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return True
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def __ne__(self, other):
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return not self.__eq__(other)
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def __str__(self):
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return "{{{}}}".format(', '.join("'{}': {}".format(k, getattr(self, k)) for k, v in six.iteritems(self._values)))
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@classmethod
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def register_for_keyspace(cls, keyspace):
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connection.register_udt(keyspace, cls.type_name(), cls)
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@classmethod
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def type_name(cls):
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"""
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Returns the type name if it's been defined
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otherwise, it creates it from the class name
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"""
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if cls.__type_name__:
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type_name = cls.__type_name__.lower()
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else:
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camelcase = re.compile(r'([a-z])([A-Z])')
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ccase = lambda s: camelcase.sub(lambda v: '{}_{}'.format(v.group(1), v.group(2)), s)
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type_name = ccase(cls.__name__)
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# trim to less than 48 characters or cassandra will complain
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type_name = type_name[-48:]
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type_name = type_name.lower()
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type_name = re.sub(r'^_+', '', type_name)
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cls.__type_name__ = type_name
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return type_name
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def validate(self):
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"""
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Cleans and validates the field values
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"""
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pass
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for name, field in self._fields.items():
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v = getattr(self, name)
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if v is None and not self._values[name].explicit and field.has_default:
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v = field.get_default()
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val = field.validate(v)
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setattr(self, name, val)
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class UserTypeMetaClass(type):
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def __new__(cls, name, bases, attrs):
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field_dict = OrderedDict()
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field_defs = [(k, v) for k, v in attrs.items() if isinstance(v, columns.Column)]
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field_defs = sorted(field_defs, key=lambda x: x[1].position)
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def _transform_column(field_name, field_obj):
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field_dict[field_name] = field_obj
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field_obj.set_column_name(field_name)
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attrs[field_name] = models.ColumnDescriptor(field_obj)
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# transform field definitions
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for k, v in field_defs:
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# don't allow a field with the same name as a built-in attribute or method
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if k in BaseUserType.__dict__:
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raise UserTypeDefinitionException("field '{}' conflicts with built-in attribute/method".format(k))
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_transform_column(k, v)
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# create db_name -> model name map for loading
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db_map = {}
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for field_name, field in field_dict.items():
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db_map[field.db_field_name] = field_name
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attrs['_fields'] = field_dict
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attrs['_db_map'] = db_map
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klass = super(UserTypeMetaClass, cls).__new__(cls, name, bases, attrs)
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return klass
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@six.add_metaclass(UserTypeMetaClass)
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class UserType(BaseUserType):
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__type_name__ = None
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"""
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*Optional.* Sets the name of the CQL type for this type.
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If not specified, the type name will be the name of the class, with it's module name as it's prefix.
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"""
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